Biofuels face their biggest test yet — whether they can power fighter jets and tanks in battle at prices the world’s best-funded military can afford.

The U.S. Air Force is set to certify all of its 40-plus aircraft models to burn fuels derived from waste oils and plants by 2013, three years ahead of target, Air Force Deputy Assistant Secretary Kevin Geiss said. The Army wants 25 percent of its energy from renewable sources by 2025. The Navy and Marines aim to shift half their energy use from oil, gas and coal by 2020.

“Reliance on fossil fuels is simply too much of a vulnerability for a military organization to have,” Navy Secretary Raymond Mabus said in an interview. “We’ve been certifying aircraft on biofuels. We’re doing solar and wind, geothermal, hydrothermal, wave, things like that on our bases.”

Yet the United States, stung by an oil embargo during the 1973 Arab- Israeli war, won’t deploy biofuels beyond testing until prices tumble. The Air Force wants them “cost-competitive” with traditional fuel, for which it pays $8 billion a year. Producers see it the other way around, saying they need big buyers before building refineries to help slash costs, according to Honeywell International Inc., which developed a process to make biofuels.

“The first few widgets are always more expensive than the billionth,” said James Rekoske, vice president of renewable energy at Honeywell’s UOP unit. “That’s where we’re at.” Honeywell expects to have delivered about 800,000 gallons of biojet fuel from 2009 through early 2012.

Rekoske said prices need to dive to $3 to $4 a gallon from more than $10 now. Refineries, costing about $300 million each, are “mission critical” and a giant customer like the U.S. government is necessary to carry production to the next level.